(1) Field of the Invention
This invention relates to cement mixers and, more particularly, to a cement mixer adapted to automatically mix small batches of concrete from reservoirs of cement, aggregate, water and additives.
(2) Description of the Prior Art
Cement mixers mounted to the chassis of vehicles are known in the art. Such cement mixers make concrete by mixing aggregate, cement and water together in one mixing bin. The cement mixers then travel to one or more work sites and selectively deposit a predetermined amount of concrete at each site. Typically, the concrete is continually agitated in the mixing bin to prevent setting of the mixture.
Additives, such as admixtures, may be blended with the concrete mixture. Admixtures are substances which alter the normal properties of mortars or concrete so as to improve them for a particular purpose. Admixtures are frequently used to entrain air, increase workability, accelerate or retard setting, provide a pozzolanic reaction with lime, reduce shrinkage and reduce bleeding.
The time needed for the setting of concrete can be greatly reduced by using the proper admixture. Conventional cement mixers mounted to a vehicle's chassis can, at best, deposit fast setting concrete at only one work site.
Accordingly, it is an object of this invention to provide a cement mixer which mixes an amount of concrete having an additive, such as a fast setting additive, as required at a particular work site.
It is yet another object of this invention to provide a cement mixer which can accurately dispense an additive to a concrete mixture as required at a particular work site.
It is also known in the art to transport and mix concrete along an elongated trough by means of a helical screw or auger fin. Concrete having a fast setting additive tends to clog both the auger fin and the area between an inner surface of an auger boot and an outer edge of the auger fin. In such prior art devices the concrete is not sufficiently mixed and backs up in the auger boot.
Therefore, it is another object of the present invention to provide a mixing auger which has improved mixing capabilities and will not become clogged when mixing fast setting concretes.